This research is aimed at elucidating: certain conformational, metabolic, and mechanistic aspects of the gonadotropins, lutropin and choriogonadotropin; the nature of the biotransformation which renders corticotropin biologically inactive with retention of immunoactivity; conformational and biologic action studies on somatotropin and choriomammatropin; the physiochemical characteristics of the pituitary mitogenic factors; and the biophysical parameters and (brain) binding parameters of the peptide opiate agonists which correspond to carboxyl-terminal fragments from B-lipotropin. Physical studies will involve circular dichroism, fluorescence, electron-spin-resonance, and hydrodynamics; chemical studies will involve amino acid composition determinations, end-group analysis, and modification. Lutropin mechanism-of-action studies will pertain mainly to Leydig cells.